Cine MR Imaging of Aortic Dissection ; Comparison with Spin-echo MR Imaging.

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Purpose of this study is to evaluate the role of cine magnetic resonance imaging (cine MR) in the diagnosis of aortic dissection, we reviewed both spin-echo MR imaging (spin-echo MR) and cine MR of 53 patients that had been documented by CT in 53 patients, aortography in 30, and surgery in five. They were divided into three groups ; double-barreled type (n=30), thrombosed type (n=18), and penetrating atherosclerotic ulcers (n=5), according to the CT features. Thirteen patients had type A,three type A+B and 37 type B dissections. In the double-barreled type, identification of the intimal flap, and true and false lumen differntiation were possible with spin-echo MR in 29 of 30 patients, and on cine MR in all 30. Variable intensities in the true and false lumens were shown on spin-echo MR,whereas flowing blood of both lumens was always visualized as a hyperintensity, and slow flow and partial thrombus as a hypointensity on cine MR.The small entry was identified as a signal void in the fal … More se lumen in 26 patients on spin-echo MR,and in 24 on cine MR.In other two patients, signal void via the large entry was not observed on cine MR.To-and-fro movement of flow via the communicating orifice could be identified in all 3 patients on cine MR,by stting the optimal axial plane of cine MR to the communicating orifice as a reference of a signal void seen on spin-echo MR.Re-entry was identified in 4 out of 6 patients with attempt to set the optimal plane of cine MR.In 18 patients with thrombosed type, the presence or absence of flow in the false lumen could not be evaluated by spin-echo MR alone, because of thickened aortic wall (n=7) or showing the various intensities such as bright (n=4), and dark (n=3), whereas on cine MR,the thrombosed false lumen was visualized as a hypointensity (n=16), suggesting no flow in the false lumen, and as a hyperintensity (n=2) mimicking double-barreled type. Outpouching projecting from the true into false lumens of ulcerlike projection (ULP) (n=8) and penetrating atherosclerotic ulcer (n=5) was observed as a signal void on spin-echo MR,and as a hyperintensity on cine MR,which features were similar to that of aortography. Spin-echo signal intensities alone were not accurate indicator in differentiating thrombus from flow-related enhancement. Because cine MR images are sensitive to the movement of flowing blood, they may allow signal produced by flow to be differentiated with more clinical confidence from that of intraluminal abnormality and thus complement findings from spin-echo images. In conclusion, cinematic display of cine MR facilitates more easy recognition of presence or absence of flow in the false lumen, and signal void via the intimal tear during cardiac cycle, simulating real-time cardiac imaging, therfore cine MR provides additional and physiologic information in the evaluaito of aortic dissection. Less